The use of wireless networking continues to grow at a rapid pace. Wireless networks are attractive for a number of reasons. They are convenient, they allow flexibility and roaming, and can support dynamic environments. Furthermore, they are relatively easy to install when compared with their wired counterparts. In some cases, for example in older buildings, they may be cheaper to deploy. An entire network can be put together in a matter of hours rather than days with no need for wiring or rewiring. In many scenarios, wireless networks can have a lower cost of ownership than their wired counterparts despite the cheaper cost of wired LAN cards.
As wireless networking becomes more popular, the number of network devices participating in wireless networks may increase. This in turn can lead to increased contention for the wireless network resources, in particular the wireless network bandwidth. Contention in a wireless network can be more problematic than in wired networks because it is relatively more expensive to recover from a collision (e.g. two or more nodes attempting to transmit simultaneously) in wireless networks.
In the IEEE 802.11 standard, IEEE std. 802.11-1999, published 1999 and later versions (hereinafter “IEEE 802.11 standard) for the wireless LAN (WLAN), the medium access control (MAC) protocol is the main element that determines the efficiency in sharing the limited communication bandwidth of the wireless channel. The fundamental access method of the IEEE 802.11 MAC is a distributed coordination function (DCF) known as carrier sense multiple access with collision avoidance, or CSMA/CA, a random access CSMA-based collision avoidance scheme. In general and according to the IEEE 802.11 standard, the DCF works as follows:
For a station to transmit, the station first determines whether the wireless medium is idle for greater than or equal to a DIFS (Distributed Interframe Spacing) period, or an EIFS (Extended Interframe Spacing) period. If yes, it will transmit immediately. If the first transmission fails or the medium is not idle, the backoff procedure will be invoked for the station. The station determines a random backoff interval counter by randomly selecting a value from the interval [0, CW]. The backoff interval counter is initialized to the randomly selected value and managed as follows: The counter is decremented for each medium idle time slot that the medium is idle. If the medium is not determined to be busy and the backoff interval counter of the station is decremented to zero, the transmission may proceed.
As can be seen from the above, the contention window determines the idle backoff time slots and packet collisions in each contention cycle. So the selection of the contention window CW can significantly impact the performance of the 802.11 MAC. In the standard 802.11 MAC, the contention window selection generally follows the following two rules:                1) The contention window CW is doubled every time following an unsuccessful attempt to transmit until the maximum contention widow size of CWmax for the medium is reached. A retry will be performed by the station for the frame.        2) The contention window CW will be reset to the minimum contention window size CWmin for the medium following a successful transmission or when a retry counter reaches its limit.        
It has been observed that the throughput performance of the standard IEEE802.11 MAC protocol does not handle highly loaded wireless local networks well. In particular when the number of active stations increases, the system throughput degrades significantly due to the high collision rate detected. As a result, there is a need in the art for the various embodiments of the present invention.